Skip to main content
. 2016 Mar;89(3):323–334. doi: 10.1124/mol.115.101758

Fig. 1.

Fig. 1.

Enhancement of endogenous Kv7.5 current in A7r5 cells by isoproterenol depends on activation of endogenous βARs and PKA. (A) Representative traces of endogenous Kv7.5 currents recorded in an A7r5 cell before (control, left panel), after 5 minutes in the presence of 1 μM isoproterenol (middle panel), and following addition of 1 μM XE991 (right panel) (C = 151 pF, representative of 11 similar experiments). (B) Current-voltage relationships of endogenous Kv7.5 current densities recorded in A7r5 cells before (control, solid circles), after 5 minutes of treatment with 1 μM isoproterenol (open circles), and after 10 minutes of treatment with 1 μM isoproterenol in combination with 1 μM XE991 (solid triangles). The asterisks (*) indicate significant difference from control, P < 0.05, one-way repeated-measures analysis of variance (ANOVA), n = 5–11. (C) Conductance-voltage relationships of endogenous Kv7.5 channels normalized to maximal conductance (Gmax) before (solid circles, n = 5) and after addition of 1 μM isoproterenol (open circles, n = 5) fitted to the Boltzmann equation (solid lines). Absolute values of conductance densities are shown in the inset. (D) Deactivation tail currents recorded at −120 mV before (black) and after addition of 1 μM isoproterenol (red), fitted by a single exponential function (solid lines). Endogenous Kv7.5 channels were activated by 5-second steps to −20 mV, followed by a 1-second step to −120 mV; five traces were averaged for each condition. The inset shows tail currents normalized to peak amplitude in order to highlight the differences in deactivation kinetics. (E) Normalized currents recorded at −20 mV in control (black bar) and in the presence of the following: 1 μM isoproterenol (ISO, open bar, n = 5); 10 μM propranolol (P, dark gray bar, n = 4); 10 μM propranolol plus 1 μM isoproterenol (P + ISO, dark gray striped bar, n = 4); 1 μM KT5720 (KT, light gray bar, n = 4); and 1 μM KT5720 plus 1 μM isoproterenol (KT + ISO, light gray striped bar, n = 4). The asterisks (*) indicate significant difference from control (P < 0.05, one-way ANOVA on ranks).